The present invention relates generally to the field of flue gas treatment for boilers, and in particular to a new and useful method and apparatus for more efficient wet cooling of boiler exhaust gases, and more particularly to providing cooling water for dehumidification of boiler flue gasses even in areas where water is scarce.
In order to remove moisture from flue gas, for example for oxycombustion, regenerable solvent advanced technology (RSAT™) scrubber, or other carbonaceous fuel burning or flue gas treatment process, one method is to use quench cooling and to control the spray water temperature to achieve the desired outlet gas saturation temperature. One such method is taught in U.S. Pat. No. 7,585,476 but this concept could be applied to any method that cools flue gas to remove a constituent such as water by controlling the saturation temperature. U.S. Pat. No. 7,585,476 is incorporated herein by reference
In current approaches, a cooling tower is used to cool the water used within a quench cooler cooling surface. It is known in the industry that wet evaporative cooling is less costly and more effective than dry cooling, but it requires a significant amount of water which is evaporated to dissipate the heat removed from the cooling water. The present invention takes advantage of the water condensed from the flue gas within the quench cooler by using it in the wet cooling tower as make-up for evaporation.
Prior art solutions have also been limited in that they require a cooling coil in the wet flue gas desulfurization scrubber (“WFGD”). One such solution is taught in U.S. patent application Ser. No. 12/830,850, which is herein incorporated by reference.